Carrier pigeons.
1. Speaking tube; for distances up to say 300 feet, 3⁄4″ to 1″ bore tubes.
2. Telephone; any distance.
3. Telegraph; any distance.
4. By signals—(a) Wire or cord and bell; (b) sight signals, such as the semaphore, lamps, heliograph, flags, and other devices; (c) by sound, such as a bell, trumpet, siren, whistle, &c. See [Section 105].
5. By pneumatic despatch: that is, by forcing a piston carriage containing the message or small parcel through a tube by compressed air.
6. Carrier pigeons.
[368]. Signalling dials and bevel gearing.
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